Communication methods, apparatuses and system for sharing network resources

ABSTRACT

A communications method enables a path computation element (PCE) to notify path computation clients (PCCs) about the shared resources of independent label switch paths by allowing a PCE to send an association object with a new association type to PCC. A PCE Communication Protocol extension that associates label-switched paths (LSPs) whose ingress, or egress, or both ingress and egress are different for resource sharing to avoid path computation failures or duplicate allocation of resources during common links for new LSPs created during an update of end-to-end (E2E) LSP. The PCC employs Resource Reservation Protocol (RSVP) for LSP signalling, PCC forwards path message information along with association object to the RSVP for LSP signalling. The RSVP uses the association object in its reservation message for LSP setup.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2018/119847, filed on Dec. 7, 2018, which claims priority toIndian Patent Application No. IN201731044887, filed on Dec. 13, 2017.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The present subject matter described herein, in general, relates totraffic engineered networks. More particularly, it relates to amechanism for a path computation element (PCE) to notify pathcomputation client(s) (PCCs) about shared resources of independent labelswitch paths.

BACKGROUND

Abstraction of network resources is a technique that can be applied to asingle network domain or across multiple domains to create a singlevirtualized network that is under the control of a network operator orthe customer of the operator that actually owns the network resources.

Abstraction and Control of Traffic Engineered Networks (ACTN) refers tothe set of virtual network operations needed to orchestrate, control andmanage large-scale multi-domain TE networks thereby facilitating networkprogrammability, automation, efficient resource sharing, and end-to-end(E2E) virtual service aware connectivity and network functionvirtualization (NFV) services. The ACTN facilitates virtual networkoperation via the creation of a single virtualized network or a seamlessservice.

PCE Communication Protocol (PCEP) facilitates communication between aPCC and a PCE, or between PCE and PCE, for the purpose of computation ofMultiprotocol Label Switching (MPLS) for traffic engineeringlabel-switched path (TE LSP) characteristics. Thus, the PCEP providesmechanisms for PCEs to perform path computations in response to PCCsrequests. While the PCEP explicitly makes no assumptions regarding theinformation available to a PCE, it also makes no provisions for the PCEto control timing and sequence of path computations within and acrossPCEP sessions.

Significantly, the PCE is a network entity capable of computing anetwork path or route based on a network graph, and of applyingcomputational constraints during the computation. The PCE entity islocated within a network node or component, on an out-of-network server,etc. For example, a PCE would be able to compute the path of a TE LSP byoperating on the traffic engineering database (TED) and consideringbandwidth and other constraints applicable to the TE LSP servicerequest.

The PCC is also a network entity which can be any client applicationthat is requesting a path computation to be performed by the PCE. A PCCcan have PCEP sessions with more than one PCE, and similarly a PCE mayhave PCEP sessions with a plurality of PCCs.

Implementing ACTN using PCE and PCEP. A hierarchical PCE architecture isthe key to ACTN framework, where in the domain controllers (or PhysicalNetwork Controller (PNC)) have the control only to its specific domainand the super controller has the global view of all the domains and cancompute and setup end to end multi-domain and multi-layer path.

The Multi-Domain Service Coordinator (MDSC) is a functional block thatimplements the main ACTN functions such as multi-domain coordination,virtualization/abstraction, customer mapping/translation, and virtualservice coordination. The MDSC co-ordinates with domain controllers tocompute E2E path and MDSC further breaks the path into per-domain LSPsegments. Domain controllers of corresponding LSP segment furtherinitiate the path setup process with in its domain.

Significantly, in ACTN architecture, the MDSC has complete/abstracttopology information of the complete network, and is therefore capableof computing E2E with the requisite constraints. The MDSC breaks an E2Epath into per-domain LSP segments and requests the corresponding domaincontroller of the domain to provision this LSP in the network, asillustrated in FIG. 1 . The MDSC employs PCEP protocol for communicationwith PNC's (who are the domain controllers). When all domain LSP's areup then the MDSC stitches a multi-domain path.

FIG. 1A illustrates an end-to end path computation, requested at theMDSC via the domain controllers, as other approaches. The MDSC thencomputes an end to end path (A to F) either by itself or by employing achild PCE. The MDSC further breaks the path into per-domain LSPsegments.

In the scenario illustrated in FIG. 1B, in step 1, the MDSC sends a PathComputation initiate (PCInitiate) message, for LSP A to C, to Domain 1.In step 2, the MDSC sends the PCInitiate message, for LSP C to E, toDomain 3. In step 3, the MDSC sends the PCInitiate, for LSP E to F, toDomain 4.

In the scenario illustrated in FIG. 1C, in step 1, the PNC sends a pathcomputation state report (PCRpt) message for LSP A to C to the MDSC. Instep 2, the PNC sends a PCRpt message for LSP C to E to the MDSC. Instep 3, the PNC sends a PCRpt message for LSP E to F to the MDSC.Notably, once the MDSC (also known as Parent PCE) receives up-state fromeach LSP segment, it stitches the per-domain LSP.

In the Hierarchical solution of E2E multi-domain LSP, there exists aneed for LSP update at MDSC that can lead to the following domain LSPupdate at PNC (or domain controller)

New LSP with same ingress and different egress with respect to old LSP.

New LSP with different ingress and same egress with respect to old LSP.

New LSP with different ingress and different egress with respect to oldLSP.

New LSP with same ingress and same egress with respect to old LSP.

In all the above case, if there is common link between old the LSP andupdated/new LSP, then the resource of this common link must be sharedbetween these LSP's. If the resource of the common link is not sharedbetween the LSP's, then the domain PCE path computation may fail owingto resource shortage or duplication of resource allocation in the commonlink.

FIG. 2 illustrates an example where the master controller MDSC computesa path between A to L. The PNC's or the domain controller's setup thepaths A-B, E-F and I-L respectively, LSP1. During path update, the MDSCre-computes the E2E path between A to L, based on new constraintssimilar to -make before break (MBB) for LSP1 in MDSC. To update thisLSP1 MDSC breaks this E2E LSP to domain specific Update/Delete/CreateDomain specific LSP.

In particular, after the MDSC computes a path between A to L which isLSP1 (represented by solid line in FIG. 2 ), the PNC1 sets up a pathfrom A-B, while PNC2 sets up a path from E-F and PNC3 sets up a pathfrom I-L. At the time of global optimization/path update case, the MDSCre-computes the E2E path between A to L, based on a new constraint. Thisscenario is similar to MBB for LSP1 in MDSC. In order to update thisLSP1, the MDSC breaks the E2E LSP (i.e., LSP1) to domain specificUpdate/Delete/Create Domain specific LSP. For the new LSP, i.e., LSP2(represented by dotted line), for the Master controller it is an MBB forLSP1.

When a new LSP is being created, for the MDSC, it is an MBB for LSP1.However, for the PNC's or domain controllers, it is as follows.

PNC1—Create new LSP A-D and delete LSP A-B. Significantly, resources arenot shared in this case as this is not an update operation and alsobecause the source/destination of the two LSP's are not same.

PNC2—Create new LSP G-H and delete LSP E-F. Resources are not shared inthis case as well as this is not an update operation and also becausethe source/destination of the two LSP's are not same.

PNC3—Create new LSP K-L and delete LSP I-L. Significantly, when creatingthe new LSP K-L, there is a shared link between these two LSP's that isM-N and N-L links. If the resources are not shared between these twoLSP's on these links will cause issues due to incorrect allocation.

Accordingly, the domain controller path computation may fail orduplicate allocations may occur as shared resources are not consideredin common links (involving the hosts M-N, N-L).

Thus, the technical problem faced the state of art technologies is thatdomain controller path computation fail or produce duplicate allocationssince sharing of resources is not considered in common links for newLSP's created during an update of E2E LSP. In particular, they do notspecify any mechanism to share the resources of two independent LSP'swhere either the ingress, or the egress, or both ingress and egress aredifferent among the LSP's.

Accordingly, the objective technical problem solved by the presentdisclosure is how to share network resources of two independent LSP'swhere either ingress, or egress, or both ingress and egress aredifferent among the two LSP's.

SUMMARY

The objective of the present disclosure is to provide a mechanism for aPCE to notify a PCC about shared resource of two independent LSP's byallowing a PCE to send an association object with a new association typeto PCC. In particular, the present disclosure provides a PCEP extensionfor associating LSP's whose ingress, or egress, or both ingress andegress are different for resource sharing to avoid path computationfailures or duplicate allocations during common links for new LSP'screated during an update of E2E LSP. The PCC employs ResourceReservation Protocol (RSVP) for LSP signalling, PCC forwards pathmessage information along with association object to the RSVP for LSPsignalling. The RSVP uses the association object in its reservationmessage for LSP setup.

According to first aspect of the disclosure, there is provided acommunication method for sharing network resources, said methodcomprising the steps of receiving, by a first network apparatus, a firstpacket from a second network apparatus, wherein the first packetcomprises an association object and path information, determining, bythe first network apparatus, a first label switched path according tothe association object, and creating, by the first network apparatus, asecond label switched path according to the path information, whereinthe second label switched path shares network resources allocated to thefirst label switched path with the first label switched path.

In a first possible implementation of the method according to the firstaspect, the method prior to the receiving of the first packet comprisesthe steps of receiving, by the first network apparatus, a second packetfrom the second network apparatus, wherein the second packet comprisesthe association object and an identifier indicating the first labelswitched path, wherein the second packet indicates that the first labelswitched path is associated with the association object. Based on thesecond packet, the first network apparatus can obtain a relationshipbetween the association object and the identifier, then after receivingthe first packet, it can obtain the identifier based on the associationobject in the first packet and the relationship.

In a second possible implementation of the method according to the firstaspect, the first label switched path and the second label switched pathhave different ingress nodes or egress nodes.

In a third possible implementation of the method according to the firstaspect, the second packet is a path computation update (PCUpd) messageor a PCRpt message.

In a fourth possible implementation of the method according to the firstaspect, the first packet is a PCInitiate message.

In a fifth possible implementation of the method according to the firstaspect, the association object comprises an association type indicatingresource sharing.

According to second aspect of the disclosure, there is provided acommunication method for sharing network resources, said methodcomprising the steps of sending, by a second network apparatus, a firstpacket comprising an association object and path information to a firstnetwork apparatus, wherein the first packet instructs the first networkapparatus to determine a first label switched path according to theassociation object and create a second label switched path according tothe path information, wherein the second label switched path sharesnetwork resources allocated to the first label switched path with thefirst label switched path.

In a first possible implementation of the communication method accordingto the second aspect, prior to the sending of the first packet, saidmethod comprises the steps of sending, by the second network apparatus,a second packet to the first network apparatus, wherein the secondpacket comprises the association object and an identifier indicating thefirst label switched path, wherein the second packet indicates that thefirst label switched path is associated with the association object.

In a second possible implementation of the communication methodaccording to the second aspect, the first label switched path and thesecond label switched path have different ingress nodes or egress nodes.

In a third possible implementation of the communication method accordingto the second aspect, the second packet is a PCUpd message or a PCRptmessage.

In a fourth possible implementation of the communication methodaccording to the second aspect, the first packet is a PCInitiatemessage.

In a fifth possible implementation of the communication method accordingto the second aspect, the association object comprises an associationtype indicating resource sharing.

According to third aspect of the disclosure, there is provided a firstnetwork apparatus for sharing network resources comprising a transceiverunit and a processing unit. The transceiver unit configured to receive afirst packet comprising an association object and path information, andthe processing unit configured to determine a first label switched pathaccording to the association object, and create a second label switchedpath according to the path information, wherein the second labelswitched path shares network resources allocated to the first labelswitched path with the first label switched path.

In a first possible implementation of the first network apparatusaccording to the third aspect, the transceiver unit is configured toreceive a second packet before receiving the first packet, wherein thesecond packet comprises the association object and an identifierindicating the first label switched path, wherein the second packetindicates that the first label switched path is associated with theassociation object.

In a second possible implementation of the first network apparatusaccording to the third aspect, the first label switched path and thesecond label switched path have different ingress nodes or egress nodes.

In a third possible implementation of the first network apparatusaccording to the third aspect, the second packet is a PCUpd message or aPCRpt message.

In a fourth possible implementation of the first network apparatusaccording to the third aspect, the first packet is a PCInitiate message.

In a fifth possible implementation of the first network apparatusaccording to the third aspect, the association object comprises anassociation type indicating resource sharing.

According to fourth aspect of the disclosure, there is provided secondnetwork apparatus for sharing network resources comprising a transceiverunit configured to send a first packet comprising an association objectand path information, wherein the first packet instructs the firstnetwork apparatus to determine a first label switched path according tothe association object and create a second label switched path accordingto the path information, wherein the second label switched path sharesnetwork resources allocated to the first label switched path with thefirst label switched path.

In a first possible implementation of the second network apparatusaccording to the fourth aspect, the transceiver unit is configured tosend a second packet before sending the first packet, wherein the secondpacket comprises the association object and an identifier indicating thefirst label switched path, wherein the second packet indicates that thefirst label switched path is associated with the association object.

In a second possible implementation of the second network apparatusaccording to the fourth aspect, the first label switched path and thesecond label switched path have different ingress nodes or egress nodes.

In a third possible implementation of the second network apparatusaccording to the fourth aspect, the second packet is a PCUpd message ora PCRpt message.

In a fourth possible implementation of the second network apparatusaccording to the fourth aspect, the first packet is a PCInitiatemessage.

In a fifth possible implementation of the second network apparatusaccording to the fourth aspect, the association object comprises anassociation type indicating resource sharing.

According to fifth aspect of the disclosure, there is providedcommunication system for sharing network resources comprising a firstnetwork apparatus and a second network apparatus. The first networkapparatus comprises a first transceiver unit configured to receive afirst packet comprising an association object and path information, anda processing unit configured to determine a first label switched pathaccording to the association object, and create a second label switchedpath according to the path information, wherein the second labelswitched path shares network resources allocated to the first labelswitched path with the first label switched path. The second networkapparatus comprises a second transceiver unit configured to send thefirst packet.

In a first possible implementation of the system according to the fifthaspect, the first transceiver unit is configured to receive a secondpacket before receiving the first packet, wherein the second packetcomprises the association object and an identifier indicating the firstlabel switched path, wherein the second packet indicates that the firstlabel switched path is associated with the association object.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1A illustrates the objective technical problem of the presentdisclosure.

FIG. 1B also illustrates the objective technical problem of the presentdisclosure.

FIG. 1C also illustrates the objective technical problem of the presentdisclosure.

FIG. 2 illustrates a reference technical solution to the objectivetechnical problem of the present disclosure.

FIG. 3 illustrates an Internet Protocol version 4 (IPv4) ASSOCIATIONObject format, in accordance with an embodiment of the present subjectmatter.

FIG. 4 illustrates an Internet Protocol version 6 (IPv6) ASSOCIATIONObject format, in accordance with an embodiment of the present subjectmatter.

FIG. 5A illustrates resource sharing in Association Object, inaccordance with an embodiment of the present subject matter.

FIG. 5B illustrates the ASSOCIATION object formats for IPv4 and IPv6, inaccordance with an embodiment of the present subject matter.

FIG. 6A illustrates a block diagram of the system, in accordance with anembodiment of the present subject matter.

FIG. 6B illustrate a block diagram of the system, in accordance with anembodiment of the present subject matter.

FIG. 7 illustrates a first network apparatus, in accordance with anembodiment of the present subject matter.

FIG. 8 illustrates a second network apparatus, in accordance with anembodiment of the present subject matter.

FIG. 9 illustrates a flowchart of a communication method performed by aPNC, in accordance with an embodiment of the present subject matter.

FIG. 10 illustrates a flowchart of a communication method performed by aMDSC, in accordance with an embodiment of the present subject matter.

It is to be understood that the attached drawings are for purposes ofillustrating the concepts of the disclosure and may not be to scale.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosure isprovided below along with accompanying figures that illustrate theprinciples of the disclosure. The disclosure is described in connectionwith such embodiments, but the disclosure is not limited to anyembodiment. The scope of the disclosure is limited only by the claimsand the disclosure encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of thedisclosure. These details are provided for the purpose of example andthe disclosure may be practiced according to the claims without some orall of these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the disclosurehas not been described in detail so that the disclosure is notunnecessarily obscured.

In the present disclosure, “PCC” refers to any client applicationrequesting a path computation to be performed by a PCE.

In the present disclosure, “PCE” refers to an entity (component,application, or network node) that is capable of computing a networkpath or route based on a network graph and applying computationalconstraints.

In the present disclosure, “PCEP Peer” refers to any element involved ina PCEP session (i.e., a PCC or a PCE).

In the present disclosure, “MDSC” refers to a control entity thatoversees the specific aspects of the different domains and builds asingle abstracted E2E network topology to coordinate E2E pathcomputation and path/service provisioning. In ACTN framework, the MDSCrealizes this function by coordinating the per-domain PNCs in ahierarchy of controllers.

In the present disclosure, “PNC” refers to a Physical Network Controllerthat is responsible for controlling devices or NEs under its directcontrol. Its functions can be implemented as part of an SDN domaincontroller, a Network Management System (NMS), an Element ManagementSystem (EMS), an active PCE-based controller or any other means todynamically control a set of nodes.

In the present disclosure, “RSVP” refers to a resource reservation setupprotocol designed for an integrated services Internet. It providesreceiver-initiated setup of resource reservations for multicast orunicast data flows, with good scaling and robustness properties.

In the present disclosure, “ASSOCIATION group” refers to a genericmechanism to create an association of LSPs.

In the present disclosure, “ASSOCIATION object” refers to an object usedto associate LSPs with each other.

In the present disclosure, “PCInitiate” is a PCEP message sent by a PCEto a PCC to trigger LSP.

In the present disclosure, “PCUpd” is a PCEP message sent by a PCE to aPCC to update attributes of an LSP. The PCUpd message can carry morethan one LSP Update Request.

In the present disclosure, “PCRpt” is a PCEP message sent by a PCC to aPCE to report the status of one or more LSPs.

Communication Methods, apparatuses and a communication system forsharing network resources in a communications network are disclosed.While aspects are described for mechanisms that would enable a PCE tonotify the PCCs about shared resources of independent label switch pathsto avoid path computation failures or duplicate allocation of resourcesduring common links for new LSP's created during an update of E2E LSP,the present disclosure may be implemented in any number of differentcomputing systems, environments, and/or configurations, the embodimentsare described in the context of the following exemplary systems,devices/nodes/apparatus, and methods.

The present disclosure discloses a mechanism for a PCE to notify a PCCabout shared resource of two independent LSP's. It specifically focuseson enabling a PCE to send an association object with new associationtype as “Resource Sharing” to PCC so as to allow sharing of resources oftwo independent LSP's where either the ingress, or the egress, or bothingress and egress are different among the LSP's. Notably the MDSC issimilar to a PCE and the PNC can be both PCE and PCC. With respect toMDSC, PNC is PCC, but with respect to network devices PNC is PCE.

Significantly, a PCE has access to the information carried by anetwork's interior gateway protocol (IGP) and also the set of currentlyactive paths with their reserved resources for path computations. ThePCE is also capable of computing constrained paths while consideringindividual LSPs and their interactions. The active PCE functionalityallows a PCE to reroute an existing LSP or make changes to theattributes of an existing LSP, or a PCC to delegate control of specificLSPs to a new PCE.

In particular, the present disclosure provides a PCEP extension forassociating LSP's whose ingress, or egress, or both ingress and egressare different for resource sharing to avoid path computation failures orduplicate allocations during common links for new LSP's created duringan update of E2E LSP. The PCC employs RSVP for LSP signalling, PCCforwards path message information along with association object to theRSVP for LSP signalling. The RSVP uses the association object in itsreservation message for LSP setup.

The extensions of PCE association group object and messages to supportshared bandwidth in hierarchical PCE are as follows.

Existing ASSOCIATION Object. An association group is a generic mechanismto create an association of LSPs. This grouping is subsequently used todefine associations between sets of LSPs or between a set of LSPs and aset of attributes. FIG. 3 illustrates an IPv4 ASSOCIATION Object formatwhile FIG. 4 illustrates an IPv6 ASSOCIATION Object format. TheASSOCIATION Object-Type is 2 for IPv6.

Significantly, the Reserved (2-byte) must be set to 0 and ignored uponreceipt. The currently defined Flags (2-byte) are R (Removal—1 bit)which when set indicates that the requesting PCE peer requires removalof an LSP from the association group. The Association type (2-byte) isan association type, for example, protection while the Associationidentifies (ID) (2-byte) is the identifier of the association group.When combined with Type and Association Source, this value uniquelyidentifies an association group. The value 0xffff and 0x0 are reserved.The value 0xffff is used to indicate all association groups.

The Association Source (4 or 16 bytes) is an IPv4 or IPv6 address. Thismay be the Internet Protocol (IP) address of the PCEP speaker thatcreated a dynamic association, an operator configured IP address, or anIP address selected as per the local policy. The value such as 0.0.0.0or ::/128 are acceptable. The optional type-length-values (TLVs) followthe conventional PCEP TLV format. The ASSOCIATION Object is optional andmay be carried in the PCUpd, PCRpt and PCInitiate messages.

Significantly, when an LSP is delegated to a stateful PCE, the statefulPCE initiates a new association group for this LSP, or associate it withone or more existing association groups. This is done by including theASSOCIATION Object in a PCUpd message. The PCUpd message (also referredto as a Path Computation LSP Update Request message) is a PCEP messagesent by a PCE to a PCC to update attributes of an LSP. The PCUpd messagecarries more than one LSP Update Request.

The PCE initiating a new LSP, can include the association groupinformation. This is done by including the ASSOCIATION Object in aPCInitiate message.

(b) New Association type for resource sharing in Association Object. Anew Association Type for Resource Sharing has to be defined in PCEassociation group. The PCE sends an update message with associationobject for old LSP first and then sends initiate request for new LSPwith the same association ID of old LSP and association type as“Resource Sharing”. The PCC will use RSVP for LSP signalling. The PCC isequipped to forward the path message information along with associationobject to RSVP for LSP signalling. The RSVP can thus, use theassociation object in its reservation message for LSP setup, asillustrated in FIG. 5A.

The present disclosure specifically focuses on the issue of resourcesharing between two independent LSP's when either the ingress, or theegress, or both ingress and egress are different among the old andupdated LSP's. This is to avoid failure or duplicate allocation ofresources during path re-computation in common links, as sharedresources are not considered by domain controllers for the new LSP'screated during an update of an E2E LSP. To achieve the desiredobjectives, the present disclosure enables a PCE to send an updatemessage with an association object for an old LSP first. Subsequently,it sends an initiate request for new LSP with same the association ID ofold LSP and association type as “Resource Sharing” thereby ensuring thatthe two independent LSP's with either ingress or egress or both beingdifferent among the LSP's share their resources.

FIG. 9 illustrates a flowchart of the communications method performed bythe first network apparatus for sharing network resources in acommunications network. The method comprises the following steps.

Step S101, the first network apparatus receiving a second packet fromthe second network apparatus.

Step S102, the first network apparatus receiving a first packet from thesecond network apparatus.

Step S103, the first network apparatus determining a first labelswitched path according to the association object of the second packet.

Step S104, the first network apparatus creating a second label switchedpath sharing network resources allocated to the first label switchedpath, according to the path information.

FIG. 10 illustrates a flowchart of the communication method performed bythe second network apparatus for sharing network resources in acommunications network. The method comprises the following steps.

Step S201, the second network apparatus sending a second packet to thefirst network apparatus.

Step 202, the second network apparatus sending a first packet comprisingan association object and path information to a first network apparatus.

The first network apparatus is a PNC while second network apparatus is aMDSC. Notably, the first network apparatus creating a second labelswitched path according to the path information involves the PNC askingan ingress node, such as device K of FIG. 6 , to setup the LSP usingRSVP signalling using the path information. The PNC sends theassociation object to ingress node too. The ingress node creates a LSPaccording to the path information, and initiates LSP association byinserting appropriate ASSOCIATION objects in the Path message of LSPsthat are to be associated. The first label switched path and the secondlabel switched path have different ingress nodes or egress nodes, i.e.,different ingress nodes, different egress nodes, different ingress anddifferent egress.

The downstream nodes, such as device M of FIG. 6 , correlates LSPs basedon received ASSOCIATION objects. The multiple types of LSP associationare supported by the ASSOCIATION object, and downstream correlation ismade based on the type. The type is “resource sharing”. The ASSOCIATIONobject using in RSVP, hereinafter referred to as an R-object, is alittle different from the ASSOCIATION object of PCEP, hereinafterreferred to as a P-object.

The original figure of the R-object format has been illustrated in FIG.5B. The ASSOCIATION object is used to associate LSPs with each other. InE2E LSP recovery, the association must only identify LSPs that supportthe same Tunnel ID as well as the same tunnel sender address and tunnelendpoint address. For this Association Type, Association Source, andAssociation ID fields of the object uniquely identify the association.Provisions are present for the object to ensure compatibility withnon-supporting nodes as well. Notably, the Association Type is 16 bitsand indicates the type of association being identified. The AssociationID is 16 bits. A value assigned by the LSP head-end. When combined withthe Association Type and Association Source, this value uniquelyidentifies an association. The Association Source is 4 or 16 byte and anIPv4 or IPv6 address, respectively, that is associated to the node thatoriginated the association.

The first packet is a PCInitiate message and comprises associationobject and path information. The path information refers toEXPLICIT_ROUTE object (ERO) which is included in a PCInitiate message.The ERO specifies a path. The PCC creates a new LSP according to theERO. The PCInitiate message includes the association object and the ERO.

The second packet is a PCUpd message or a PCRpt message from the secondnetwork apparatus and comprises an association object and an identifierindicating the first label switched path. The association objectcomprises an association type indicating resource sharing. Theidentifier refers to PCEP-specific LSP (PLSP)-ID and each LSP has aunique PLSP-ID. The PCE includes a PLSP-ID in an update message toindicate a LSP to be updated. After receiving the update message whichcomprises association object and PLSP-ID, the PCC may maintain therelationship between association ID and PLSP-ID. So PCC can obtainPLSP-ID according to the relationship and the association object in theInitiate message. The second packet indicates that the first labelswitched path is associated with the association object.

The second label switched path shares network resources allocated to thefirst label switched path with the first label switched path. The newLSP shares network resources with the old LSP when the new LSP iscreated. Once the ingress node of the new LSP receives a Resv messagefor the new LSP, the traffic of the old LSP may be transited to the newLSP, and subsequently the old LSP may be torn down.

FIG. 6A and FIG. 6B illustrate examples where a master controller or theMDSC computes a path between hosts A to L. In particular, theyillustrate a system for routing data packets in a communicationsnetwork. This system comprises at least one first network apparatus(PNC1, PNC2, PNC3) that is adaptively configured to route data packetsamong plurality of network elements (A-L) and a second network apparatus(MDSC) that is adaptively configured to control a plurality of networkapparatuses. The first network apparatus (PNC1, PNC2, PNC3) controls aplurality of network elements (A-D, E-H, I-L). Notably, the domaincontrollers or PNC's i.e., PNC1, PNC2 and PNC 3, setup the paths A-B,E-F and I-L, respectively. The path A-B-E-F-I-M-N-L is the LSP1 or oldLSP. In FIG. 6B illustrates that PNC1 issues initiate message to createnew LSP A-D (a1) and issues update message to delete old LSP A-B (a2) tohost A. PNC2 issues PNC2 issues initiate message to create new LSP G-H(b1) to host G and issues update message to delete old LSP E-F (b2) tohost E. PNC3 issues initiate message to add association object to oldLSP I-L (c1) to host I, issues initiate message to create new LSP withassociation object K-L (c2) to host K, and issues update message todelete old LSP I-L (c3) to host I.

During global optimization/path update, the master controllerre-computes the E2E path between A to L, based on the new constraints.This is similar to MBB for LSP1 in the master controller. To update thisLSP1, the master controller breaks this E2E LSP to domain specificUpdate/Delete/Create domain specific LSP, for the new LSP.Significantly, for the master controller, this is an MBB for LSP1.

For domain controller PNC1, the re-computation of E2E path results increating new LSP involving hosts A-D with a new association type as“Resource Sharing” and deleting the old LSP involving hosts A-B. Inparticular, the PNC1 sends a PCInitiate message with same associationobject and association type as “Resource Sharing”.

For domain controller PNC2, the re-computation of E2E path also resultsin creating new LSP involving hosts G-H with new association type as“Resource Sharing” and deleting the old LSP involving hosts E-F. Inparticular, the PNC2 also sends a PCInitiate message with sameassociation object and association type as “Resource Sharing”.

For domain controller PNC3, the re-computation of E2E path results increating new LSP involving hosts K-M-N-L with a new association type asResource Sharing” and deleting the old LSP involving host I-L. Thenetwork resources such as bandwidth will be shared between the twoLSP's.

FIG. 7 illustrates the first network apparatus (100) which is a domaincontroller. The first network apparatus (100) comprises at least atransceiver unit (101) and a processing unit (103). There is also amemory unit (102). The transceiver unit (101) is configured to receive afirst packet comprising an association object and path information. Itis also configured to receive a second packet before receiving the firstpacket where the second packet comprises the association object and anidentifier indicating the first label switched path. The second packetindicates that the first label switched path is associated with theassociation object. The processing unit (103) is configured to determinea first label switched path according to the association object andcreate a second label switched path according to the path information,where the second label switched path shares network resources allocatedto the first label switched path with the first label switched path.

FIG. 8 illustrates the second network apparatus (200) which is a mastercontroller. The second network apparatus (200) comprises at least atransceiver unit (201), a processing unit (203) and a memory unit (102).The transceiver unit (201) is configured to send a first packetcomprising an association object and path information where the firstpacket instructs the first network apparatus (100) to determine a firstlabel switched path according to the association object and create asecond label switched path according to the path information. The secondlabel switched path shares network resources allocated to the firstlabel switched path with the first label switched path. The transceiverunit (201) is also configured to send a second packet before sending thefirst packet where the second packet comprises association object andidentifier indicating the first label switched path. The second packetindicates that the first label switched path is associated with theassociation object.

Significantly, the second packet is a PCUpd message, or a PCRpt messageor any similar message and the first packet is a PCInitiate message orany similar message. The first network apparatus creates label switchedpath segments between at least two of its network elements. The labelswitched path (A-B-E-F-I-M-N-L) comprises a plurality of label switchedpath segments such as the first label switched path segment (A-D, G-H,K-M, N-L), the second label switched path segment (A-B, E-F, I-M, N-L),etc. The resources allocated to the second label switched path segment(A-B) are allocated on shared basis to the first label switched pathsegment (A-D).

The advantage of the present disclosure is that it enables the domaincontroller to consider shared resource in case of E2E LSP setup inhierarchical PCE because the case of existing E2E LSP setup inhierarchical PCE, the domain controllers fail to a compute path whenresources are not available or duplicate resource allocation happens.

A person of ordinary skill in the art may be aware that in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps may be implemented byelectronic hardware, or a combination of computer software andelectronic hardware. Whether the functions are performed by hardware orsoftware depends on the particular applications and design constraintconditions of the technical solution. A person skilled in the art mayuse different methods to implement the described functions for eachparticular application, but it should not be considered that theimplementation goes beyond the scope of the present disclosure.

It may be clearly understood by a person skilled in the art that for thepurpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, reference may bemade to a corresponding process in the foregoing method embodiments, anddetails are not described herein again.

In the several embodiments provided in the present application, itshould be understood that the disclosed apparatus and method may beimplemented in other manners. For example, the described apparatusembodiment is merely exemplary. For example, the unit division is merelylogical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented through some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of the present disclosureessentially, or the part contributing to the other approach, or a partof the technical solutions may be implemented in a form of a softwareproduct. The computer software product is stored in a storage medium,and includes several instructions for instructing a computer node (whichmay be a personal computer, a server, or a network node) to perform allor a part of the steps of the methods described in the embodiment of thepresent disclosure. The foregoing storage medium includes any mediumthat can store program code, such as a Universal Serial Bus (USB) flashdrive, a removable hard disk, a read-only memory (ROM), a random accessmemory (RAM), a magnetic disk, or an optical disc.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

The invention claimed is:
 1. A sharing network resources communicationmethod implemented by a first network apparatus, wherein the sharingnetwork resources communication method comprises: receiving a first pathcomputation element protocol (PCEP) message from a second networkapparatus, wherein the first PCEP message comprises an associationobject and path information, and wherein the association objectcomprises an association type indicating resource sharing and anassociation ID identifying an association group; determining a firstlabel switched path (LSP) according to the association ID in theassociation object; and creating a second LSP according to the pathinformation, wherein the first LSP and the second LSP have differentingress nodes or egress nodes, wherein the network resources areallocated to the first LSP, and wherein the second LSP shares thenetwork resources allocated to the first LSP.
 2. The sharing networkresources communication method of claim 1, wherein prior to receivingthe first PCEP message, the sharing network resources communicationmethod further comprises receiving a second PCEP message from the secondnetwork apparatus, wherein the second PCEP message comprises anassociation object comprising the association ID and an identifierindicating the first LSP, and wherein the second PCEP message indicatesthe first LSP is associated with the association object.
 3. The sharingnetwork resources communication method of claim 2, wherein the secondPCEP message is a path computation update message.
 4. The sharingnetwork resources communication method of claim 2, wherein the secondPCEP message is a path computation report message.
 5. The sharingnetwork resources communication method of claim 1, wherein the first LSPand the second LSP have different ingress nodes and egress nodes.
 6. Thesharing network resources communication method of claim 1, wherein thefirst PCEP message is a path computation initiate message.
 7. A firstnetwork apparatus for sharing network resources, comprising: aprocessor; and a memory coupled to the processor and storinginstructions that, when executed by the processor, cause the firstnetwork apparatus to be configured to: receive, from a second networkapparatus, a first path computation element protocol (PCEP) messagecomprising an association object and path information, wherein theassociation object comprises an association type indicating resourcesharing and an association ID being an identifier of an associationgroup; determine a first label switched path (LSP) according to theassociation ID in the association object; and create a second LSPaccording to the path information, wherein the first LSP and the secondLSP have different ingress nodes or egress nodes, wherein the networkresources are allocated to the first LSP, and wherein the second LSPshares the network resources allocated to the first LSP.
 8. The firstnetwork apparatus of claim 7, wherein before receiving the first PCEPmessage, the instructions further cause the first network apparatus tobe configured to receive a second PCEP message, wherein the second PCEPmessage comprises an association object comprising the association IDand an identifier indicating the first LSP, and wherein the second PCEPmessage indicates that the first LSP is associated with the associationobject.
 9. The first network apparatus of claim 8, wherein the secondPCEP message is a path computation update message.
 10. The first networkapparatus of claim 8, wherein the second PCEP message is a pathcomputation report message.
 11. The first network apparatus of claim 8,wherein the instructions further cause the first network apparatus to beconfigured to maintain a relationship between the association ID and theidentifier indicating the first LSP.
 12. The first network apparatus ofclaim 11, wherein the instructions further cause the first networkapparatus to be configured to determine the first label switched pathaccording to the relationship and the association ID in the first PCEPmessage.
 13. The first network apparatus of claim 7, wherein the firstLSP and the second LSP have different ingress nodes and egress nodes.14. The first network apparatus of claim 7, wherein the first PCEPmessage is a path computation initiate message.
 15. The first networkapparatus of claim 7, wherein the first network apparatus is a domaincontroller having the control to a first domain, and wherein the secondnetwork apparatus is a super controller which has a global view ofmultiple domains comprising the first domain.
 16. The first networkapparatus of claim 7, wherein the first network apparatus is used as apath computation client (PCC), and wherein the second network apparatusis used as a path computation element (PCE).
 17. The first networkapparatus of claim 7, wherein the first network apparatus is physicalnetwork controller (PNC), and wherein the second network apparatus is amulti-domain service coordinator (MDSC).
 18. A second network apparatusfor sharing network resources, comprising: a processor; and a memorycoupled to the processor and storing instructions that, when executed bythe processor, cause the second network apparatus to be configured tosend a first path computation element protocol (PCEP) message comprisingan association object and path information to a first network apparatus,wherein the association object comprises an association type indicatingresource sharing and an association ID identifying an association group,wherein the resource sharing indicates that the network resources areshared by two independent label switch paths (LSPs) that are associatedwith each other by the association object wherein the first PCEP messageinstructs the first network apparatus to determine a first LSP accordingto the association ID in the association object and to create a secondLSP according to the path information, wherein the first LSP and thesecond LSP have different ingress nodes or egress nodes, wherein thenetwork resources are allocated to the first LSP, and wherein the secondLSP shares the network resources allocated to the first LSP.
 19. Thesecond network apparatus of claim 18, wherein before sending the firstPCEP message, the instructions further cause the second networkapparatus to be configured to send a second PCEP message comprising anassociation object comprising the association ID and an identifierindicating the first LSP, and wherein the second PCEP message indicatesthat the first LSP is associated with the association object.
 20. Thesecond network apparatus of claim 19, wherein the second PCEP message isa path computation update message.
 21. The second network apparatus ofclaim 19, wherein the second PCEP message is a path computation reportmessage.
 22. The second network apparatus of claim 18, wherein the firstLSP and the second LSP have different ingress nodes and egress nodes.23. The second network apparatus of claim 18, wherein the first PCEPmessage is a path computation initiate message.
 24. The second networkapparatus of claim 18, wherein the first network apparatus is a domaincontroller having the control to a first domain, and wherein the secondnetwork apparatus is a super controller which has a global view ofmultiple domains comprising the first domain.
 25. The second networkapparatus of claim 18, wherein the first network apparatus is physicalnetwork controller (PNC), and wherein the second network apparatus is amulti-domain service coordinator (MDSC).
 26. A communication system,comprising: a first network apparatus configured to: receive a firstpath computation element protocol (PCEP) message from a second networkapparatus, wherein the first PCEP message comprises an associationobject and path information, and wherein the association objectcomprises an association type indicating resource sharing and anassociation ID identifying an association group; determine a first LSPaccording to the association ID in the association object; and create asecond LSP according to the path information, wherein the first LSP andthe second LSP have different ingress nodes or egress nodes, wherein thenetwork resources are allocated to the first LSP, and wherein the secondLSP shares the network resources allocated to the first LSP; and thesecond network apparatus configured to send the first PCEP message. 27.The communication system of claim 26, wherein the second networkapparatus is further configured to before sending the first PCEPmessage, send a second PCEP message comprising an association objectcomprising the association ID and an identifier indicating the firstLSP, and wherein the second PCEP message indicates that the first LSP isassociated with the association object.